Screwdriver tool with improved linear tracking

Abstract

An automatic fastener driving tool, or an attachment, has an external depth of drive adjustment subassembly that is mounted external to the feed tube housing, yet has a simple adjustment that does not lose its setpoint easily. By placing the depth of drive mechanism outside of the interior areas of the feed tube, the slide body subassembly can be lengthened without increasing the overall length of the feed system. Certain surfaces of slide body subassembly exhibit a dovetail shape, which allows the slide body subassembly to be robustly mounted so that it is capable of operating with long fasteners while also having the nosepiece mounted in an extended position for use with those fasteners.

What is claimed is: 
     
       1. A drive apparatus for a rotatable fastener driving tool, comprising:
 a slide body structure that is actuated by relative movement, and that has an output member which creates an indexing motion, said slide body structure having a dovetail shaped body member; and 
 an elongated feed tube having a first end and a second, opposite end along a longitudinal axis, said feed tube having an open volume therewithin, said first end being open and sized and shaped to receive said slide body structure, said feed tube having an elongated slidable surface at an interior location, said slidable surface having a shape that corresponds to mate against said dovetail shaped body member, wherein during operation, said slide body structure is movable with respect to said feed tube along said slidable surface of the feed tube, which relative movement actuates said slide body structure. 
 
     
     
       2. The drive apparatus of  claim 1 , wherein:
 (a) said slide body structure comprises a slide body subassembly and a nosepiece that is adjustably affixed to said slide body subassembly; and 
 (b) said nosepiece includes said dovetail shaped body member, said nosepiece having a distal end that extends past said first end of the feed tube, and said nosepiece distal end being used to contact a surface of a workpiece. 
 
     
     
       3. The drive apparatus of  claim 2 , wherein said slide body subassembly comprises:
 a drive gear having a first axis of rotation, said drive gear having a first set of engagement extensions along one of its surfaces at a first position along said first axis of rotation, said drive gear having a set of ratchet teeth at a second position along said first axis of rotation; 
 said output member, which comprises a sprocket having a second axis of rotation that is substantially parallel to said first axis of rotation, and that is spaced-apart from said drive gear, said sprocket having a first plurality of spaced-apart protrusions along an outer curved surface at a third position along said second axis of rotation, said sprocket having a second set of engagement extensions at a fourth position along said second axis of rotation; 
 a drive belt that runs between said drive gear and said sprocket, said drive belt having a second plurality of spaced-apart protrusions along one of its surfaces, said second plurality of spaced-apart protrusions being in mechanical engagement with said first set of engagement extensions of said drive gear and being in mechanical engagement with said second set of engagement extensions of said sprocket, said drive belt being caused to move if said drive gear rotates, and said drive belt then causing said sprocket to rotate; and 
 a displacement action mechanism that causes said drive gear to rotate by way of said set of ratchet teeth. 
 
     
     
       4. The drive apparatus of  claim 3 , further comprising: a flexible collated strip of fasteners that slides over an end portion of said slide body subassembly, said flexible strip having a plurality of spaced-apart openings that engage with said first plurality of spaced-apart protrusions of the sprocket, and are thereby sequentially indexed into a drive position by rotation action of said sprocket about said second axis of rotation. 
     
     
       5. The drive apparatus of  claim 2 , wherein said slide body subassembly comprises:
 a drive gear having a first axis of rotation, said drive gear having a first set of gear teeth along one of its surfaces at a first position along said first axis of rotation, said drive gear having a set of ratchet teeth at a second position along said first axis of rotation; 
 a sprocket having a second axis of rotation that is substantially parallel to said first axis of rotation, and that is spaced-apart from said drive gear, said sprocket having a plurality of spaced-apart protrusions along an outer curved surface at a third position along said second axis of rotation, 
 
       said sprocket having a second set of gear teeth along one of its surfaces at a fourth position along said second axis of rotation;
 at least one intermediate gear having at least one intermediate axis of rotation, said at least one intermediate gear having at least one third set of gear teeth that are in mechanical engagement with said first set of gear teeth of said drive gear and being in mechanical engagement with said second set of gear teeth of said sprocket, said at least one intermediate gear being caused to move if said drive gear rotates, and said at least one intermediate gear then causing said sprocket to rotate; and 
 a displacement action mechanism that causes said drive gear to rotate. 
 
     
     
       6. The drive apparatus of  claim 5 , further comprising: a flexible collated strip of fasteners that slides over an end portion of said slide body subassembly, said flexible strip having a plurality of spaced-apart opening's that engage with said plurality of spaced-apart protrusions of the sprocket, and are thereby sequentially indexed into a drive position by rotation action of said sprocket about said second axis of rotation. 
     
     
       7. The drive apparatus of  claim 1 , wherein: said elongated slidable surface of the feed tube comprises at least one linear bearing strip, made of a material having a low coefficient of friction. 
     
     
       8. The drive apparatus of  claim 7 , further comprising: at least one elongated guiding surface located on a first side of said slide body subassembly, wherein said at least one linear bearing strip is located on a second, opposite side of said slide body subassembly, and both said at least one elongated guiding surface and said at least one linear bearing strip tend to support and guide said slide body subassembly as it slides inward and outward with respect to said feed tube. 
     
     
       9. A drive apparatus for a rotatable fastener driving tool, comprising:
 a slide body subassembly that is actuated by relative movement, and that has an output member which creates an indexing motion; 
 an elongated feed tube having a first end and a second, opposite end along a longitudinal axis, said feed tube having an open volume therewithin, said first end being substantially open and sized and shaped to receive said slide body subassembly, said feed tube having an elongated slidable surface and, during operation, said slide body subassembly is movable with respect to said feed tube, which relative movement actuates said slide body subassembly; 
 an elongated nosepiece that is adjustably affixed to said slide body subassembly, said nosepiece having a third end and a fourth, opposite end along an axis of movement that is substantially parallel to said longitudinal axis, said third end extending past said first end of the feed tube so as to contact a surface of a workpiece, said fourth end extending toward said second end of the feed tube and having a first contact surface; and 
 a depth of drive subassembly that is mounted proximal to the second end of said feed tube, said depth of drive subassembly including a movable member that has a second contact surface, said first contact surface of the fourth end of the nosepiece coming into mechanical communication with said second contact surface at the end of a fastener driving cycle. 
 
     
     
       10. The drive apparatus of  claim 9 , wherein:
 (a) said first contact surface comprises an edge portion of said fourth end of the nosepiece that is angled; and 
 (b) said second contact surface comprises an inclined portion of said movable member that is adjustable in a direction that is substantially perpendicular to said longitudinal axis. 
 
     
     
       11. The drive apparatus of  claim 9 , wherein said depth of drive subassembly comprises:
 a housing; 
 an adjusting screw having a hand-adjustable knob, said adjusting screw extending in a direction that is substantially perpendicular to said longitudinal axis, said adjusting screw having first mating screw threads; 
 said movable member with said second contact surface, in which said second contact surface is angled so as to not be parallel or perpendicular to said longitudinal axis, said movable member having second mating screw threads that engage said first mating screw threads, so that if said hand-adjustable knob is rotated, then said movable member is moved along said substantially perpendicular direction. 
 
     
     
       12. The drive apparatus of  claim 11 , wherein:
 (a) if said movable member is adjusted in a first substantially perpendicular direction, then said first contact surface of the nosepiece will come into contact with said second contact surface of the movable member at a point earlier during said fastener driving cycle, thereby leaving the fastener at a higher position in the workpiece; and 
 (b) if said movable member is adjusted in a second substantially perpendicular direction that is opposite to said first substantially perpendicular direction, then said first contact surface of the nosepiece will come into contact with said second contact surface of the movable member at a point later during said fastener driving cycle, thereby leaving the fastener at a deeper position in the workpiece. 
 
     
     
       13. The drive apparatus of  claim 11 , further comprising:
 a locking latch member with a hand-actuated tab, a compression spring to bias said locking latch member in a linear direction, and a latch retainer; 
 wherein: (i) said hand-adjustable knob has a plurality of recesses that engage with said locking latch member to hold a position of said adjusting screw, so as to prevent unintentional movement of said movable member; (ii) said tab is used to depress said compression spring to release said locking latch member from said hand-adjustable knob, so as to allow the adjusting screw to be rotated to a new position. 
 
     
     
       14. A drive apparatus for a rotatable fastener driving tool, comprising:
 a slide body subassembly that is actuated by relative movement, and that has an output member which creates an indexing motion; 
 an elongated feed tube having a first end and a second, opposite end along a longitudinal axis, said feed tube having an open volume therewithin, said first end being substantially open and sized and shaped to receive said slide body subassembly, said feed tube having an elongated slidable surface and, during operation, said slide body subassembly is movable with respect to said feed tube, which relative movement actuates said slide body subassembly; 
 an elongated nosepiece that is adjustably affixed to said slide body subassembly, said nosepiece having a third end and a fourth end at opposite positions along an axis of movement that is substantially parallel to said longitudinal axis, said third end extending past said first end of the feed tube so as to contact a surface of a workpiece, said fourth end extending toward said second end of the feed tube; and 
 a depth of drive subassembly that is mounted at an external location with respect to said feed tube, said depth of drive subassembly having an adjustable mechanism that engages with said fourth end of the nosepiece. 
 
     
     
       15. The drive apparatus of  claim 14 , wherein:
 (a) said fourth end of the nosepiece has a first contact surface; 
 (b) said adjustable mechanism of the depth of drive subassembly comprises a movable member that has a second contact surface; and 
 (c) said first contact surface of the fourth end of the nosepiece coming into mechanical communication with said second contact surface at the end of a fastener driving cycle. 
 
     
     
       16. The drive apparatus of  claim 15 , wherein said depth of drive subassembly comprises:
 a housing that is mounted external to said feed tube; 
 an adjusting screw having a hand-adjustable knob, said adjusting screw extending in a direction that is substantially perpendicular to said longitudinal axis, said adjusting screw having first mating screw threads; and 
 said movable member, in which said second contact surface is angled so as to not be parallel or perpendicular to said longitudinal axis, said movable member having second mating screw threads that engage said first mating screw threads, so that if said hand-adjustable knob is rotated, then said movable member is moved along said substantially perpendicular direction; 
 and wherein: (i) said adjusting screw is mounted external of said feed tube; however, (ii) a portion of said movable member is positioned to extend through an opening of said feed tube so as to engage with said fourth end of the nosepiece. 
 
     
     
       17. The drive apparatus of  claim 16 , wherein:
 (a) if said movable member is adjusted in a first substantially perpendicular direction, then said first contact surface of the nosepiece will come into contact with said second contact surface of the movable member at a point earlier during said fastener driving cycle, thereby leaving the fastener at a higher position in the workpiece; and 
 (b) if said movable member is adjusted in a second substantially perpendicular direction that is opposite to said first substantially perpendicular direction, then said first contact surface of the nosepiece will come into contact with said second contact surface of the movable member at a point later during said fastener driving cycle, thereby leaving the fastener at a deeper position in the workpiece. 
 
     
     
       18. The drive apparatus of  claim 16 , further comprising:
 a locking latch member with a hand-actuated tab, a compression spring to bias said locking latch member in a linear direction, and a latch retainer; 
 wherein: (i) said hand-adjustable knob has a plurality of recesses that engage with said locking latch member to hold a position of said adjusting screw, so as to prevent unintentional movement of said movable member; (ii) said tab is used to depress said compression spring to release said locking latch member from said hand-adjustable knob, so as to allow the adjusting screw to be rotated to a new position.